The expression of useful foreign traits in plants is a major focus in plant biotechnology. Introduction of heterologous genes of interest into plant cells generates the desired qualities in the plants of choice (Maiti and Hunt, 1992; Wagner, 1992). Plant biotechnology is leading a rapid progress in production of economically valuable germplasm with improved characteristics or traits such as insect resistance, virus resistance, fungal resistance, herbicide resistance, bacterial or nematode pathogen resistance, cold or drought tolerance, improved nutritional value, seed oil modification, delayed ripening of fruits, and male sterility, to name a few. These germplasms provide an enhanced development in breeding programs for crop improvement as well as a better understanding of gene regulation and organization in transgenic plants.
Plant metabolic engineering is the application of genetic engineering methods to modify the nature of chemical metabolites in plants. However, for metabolic engineering, multiple genes must inserted into a single cell. Thus, there is a need for an efficient system for introducing multiple genes into single plant cells and obtaining translation of the mRNAs transcribed from the inserted genes.